Slide fastener structure employing helical fastener member



Aug. 22, 1961 H. POREPP 2,996,780

SLIDE FASTENER STRUCTURE EMPLOYING I-IELICAL FASTENER MEMBER Filed July 1, 1958 j In;

INVENTOQ: /4/v5 PO/Qf/ p United States Patent 2,996,780 SLIDE FASTENER STRUCTURE EMPLOYING HELICAL FASTENER MEMBER Hans Porepp, Am Ruhrstein 58,

Essen-Bredeney, Germany Filed July '1, 1958, Ser. No. 745,901

Claims priority, application Germany July 2, 1957 1 Claim. (Cl. 24-40516) Helical thread slide fasteners having two opposed sets of fastener elements comprising profiled helical fastener threads made of metal or preferably of a thermo-plastic material have heretofore been made in such a manner that an attachment cord is linked to the helical threads forming each set of fastener elements. Two such helical threads preferably in mesh with one another and attached to their cords, are fed to a dual needle sewing machine with two carrier strips and two slider guide cords. Each carrier strip is firmly sewn to one side of an attachment cord and one guide cord is sewn firmly to the opposite side thereof. The guide cords are necessary in order to provide a side flange of a slider with a guide surface of sufficient height above or below the fastener threads. To supply continuously at high speed the joined helical threads with attachment cords, carrier strips and guide cords to the sewing machine entails considerable difliculties. The output of usual double-needle sewing machines which have hitherto been employed, is limited by the length of the thread of the shuttle. The operator is obliged to renew the bobbin of the shuttle frequently, thereby interrupting the continuity of the sewing process.

One object of the invention is to allow working with threads of any desired length which run off large rollers so that an interruption of the sewing process is no longer necessary and thereby the output of the sewing machine is considerably increased.

Another object is to provide a slide fastener structure in which the stitching of attachment cord to the carrier strip itself defines a guide cord or strip of sufficient height to guide the slider of the fastener.

Accordingly, in a helical thread fastener according to the invention, as illustrated in FIGURES 2 and 3, the attachment cord 2 which in itself is not of sufiicient thickness to form a guide for the conventional slider is sewn to the carrier strip 4 by means of a double chain-stitch seam, whose lower-thread 5 is situated on the side of the attachment cord which is turned away from the carrier strip, as clearly shown in FIGURE '3, thus providing sufiicient thickness and making an additional conventional guide cord unnecessary.

By using a double chain-stitch seam or knot seam it is possible to wind the upper-thread 6 and the underthread 5 off separate thread spools of an; desired size, so that the operator does not need to interrupt the sewing frequently for respooling. Also it is no longer necessary to provide a special guide cord for the fastener slider as was hitherto necessary. This results because the underthread 5 of the double chain-stitch seam is formed with a chain of triple loops interlocked with a chain of loops of the upper thread to form a guide strip. This strip extends along and below the attachment cord 2 to form a satisfactory guide for the side flange of the slider of the fastener. The under-thread should therefore have a sufiicient thickness, hardness, and surface condition as is necessary for guiding the slider. The under-thread material forms a strip reinforced on both sides. The upperthread 6 of the double chain-stitch seam primarily determines the strength of the seam.

Since the inner sides of the slider flange due to its movement can cause wear of the attachment cord 2, its linking threads 3 and the under-threads 5 of the double chain-stitch seam, when textile threads are used, it is Patented Aug. 22, 1961 advantageous to link the attachment cord to the helical thread 1 by means of two parallel linking threads 3 gripped between the helical thread windings, one linking thread being very resistant against wear, and made for example of a synthetic resin such as polyamide or polyurethane thread under tension, and the other thread being a textile such as cotton thread.

In order to make the new slide fastener structure according to the invention the helical thread 1 with attachment cord 2 is fed in the vicinity of one edge of and below the carrier strip 4, to a double chain-stitch sewing machine in such a manner that the loops of the underthread 5, which are held by means of the loops of the upper-thread 6 stitched through pairs of aligned holes in the carrier strip and through the attachment cord. This forms a strip of interlocked loops extending below the attachment cord and its linking threads 3 a suificient height for guiding the fastener slider.

Since a double chain-stitch seam can be drawn from the end at which the sewing stops, two opposed and enmeshed helical threads with attachment cords may be sewn at the same time to the two carrier strips in the double chainstitch sewing machine. The direction of sewing may be effected in the direction of opening of the fastener by the slider, so that the endless sets of fastener elements become firmly bound to one another by means of an end member in a desired length. This ensures a satisfactory meshing of the helical threads and their correct positioning relatively to the carrier strips and a drawing up of the double chain-stitch seam is avoided.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawing which shows a specific arrangement thereof by way of example and in which:

FIG. 1 shows an enlarged cross-section through a helical thread with an attachment cord wound on,

FIG. 2 shows a schematic enlarged cross-section through a set of fastener elements of a helical thread fastener, and

FIG. 3 shows a longitudinal section along the line Ill-411 of FIG. 2.

Referring to the drawing, in making a helical thread slide fastener according to the invention, a profiled helical thread or stringers 1, which advantageously is made from an organic plastic material, is linked to an attachment cord 2 by means of a helical double thread 3, which is wound on cord 2 and engages each of the windings of the thread 1.

In accordance with the invention, it is advantageous to use a pair of parallel juxtaposed threads which together pass through the intermediate spaces between the helical thread windings in order to link thread 1 with the cord 2. One of threads 3 may be and preferably is very resistant to wear and advantageously consists of a polyamide or polyurethane thread under tension. The purpose of this wear resistant thread will be explained later.

After linking the attachment cord 2 to the helical thread 1, two opposed helical threads 1 with their cords, are enmeshed by means of a slider and are then fed to a double chain-stitch sewing machine together with two carrier strips 4 which are positioned above the cords 2, the cords 2 being arranged in the vicinity of the facing edges of the strips 4, so that the loops of an under-thread 5, which are held by means of loops, an upper thread 6 stitched through the carrier strip 4 and the attachment cord 2, form together with the attachment cord 2 and its linking threads a guide strip of sufficient height for the slide of the fastener. Since double chain-stitch seams have the property that they can be drawn up from the end at which sewing stops, it is necessary during the sewing of the attachment cord 2 to the carrier strip 4 to arrange that the sewing is effected in the Question of opening of the fastener by its slider. Then the endless individual or successive carrier strips will be formed together in a desired length and will have a joined end member.

When sewing with a double chain-stitch sewing machine, the upper thread 6 primarily determines the strength of the seam, whilst the loops of the under-thread 5, according to the thickness, hardness and surface condition e.g. roughness of the under-thread, strengthens the attachment cord 2 in the desired manner and adapts it to the height of the sliders to be employed.

By employment of the double chain-stitch seam in the manner mentioned, the inner sides of the slider flange on the side turned away from the helical thread 1 glide along the attachment cord 2, its linking threads 3 and the interlocked loops of upper-thread 6 and under-thread 5 of the seam. This gliding movement after a time causes wear. For this reason, one of the linking threads should be made from a wear-resistant material, which prevents the other one of the two linking threads 3 from being broken due to wear, and thus avoids damage to the fastener.

I claim:

A slide fastener structure, comprising a helical filamentary slide fastener member made of plastic material, an attachment cord disposed axially parallel to the axis of said member, a pair of juxtaposed threads helically wound around the cord, said threads having spaced turns linked to each turn of the helical fastener member and holding the same adjacent to said cord, one of said threads being formed of a synthetic resin material, a carrier-strip overlaying said cord and fastener member, and a double chain stitched seam securing. the cord to said strip, said seam having a first other thread formed with a chain of spaced loops extending through said cord with bights of the loops extending below the cord 3. distance greater than the diameter of the cord, said stitching having a second other thread formed with a chain of groups of three loops each, each group of loops of the second other thread having portions engaged with one preceding and one succeeding adjacent loop of the chain of loops of the first other thread to form a strip of fabric under the cord and under the helical slide fastener member, said strip defining with said cord and with the first named pair of threads a guide for a slider of the slide fastener.

References Cited in the file of this patent UNITED STATES PATENTS 

